If you use any payment gateway, you need to send the full credit card number from the client so the gateway can return a token that identifies the card in their vault.
You can do the same and write some JS to get the first 6 numbers and send a GET request to our API without compromising security. The BIN (first 6 numbers of credit cards) is not considered the primary account number so it's safe to send (and even store).
Like Devan stated below - "We position ourselves between Gumroad & Shopify (if they did payments)".
In the future, we plan on adding widgets that will work within our application that will cater to some of the cases you pointed out. Some of these widgets will include date/time charging (tutor offering hours/days of work) and subscription based charging (SaaS service you mentioned). Of course, we're not limited to just that.
As for the PSD, we host the file for you so all you need to do is upload the PSD and after the checkout process, the buyer can immediately download it.
If you use any payment gateway, you need to send the full credit card number from the client so the gateway can return a token that identifies the card in their vault.
You can do the same and write some JS to get the first 6 numbers and send a GET request to our API without compromising security. The BIN (first 6 numbers of credit cards) is not considered the primary account number so it's safe to send (and even store).